The present invention broadly relates to a solar salt crystallizer system and process for producing salt by solar techniques, and more particularly to an improved crystallizer arrangement and process which is adaptable for producing solar salt efficiently in climates heretofore believed unfavorable for solar salt production.
The conventional process for producing solar salt comprises an evaporation of seawater in a series of open ponds at ambient temperature in which the concentration of the salt progressively increases toward the last pond, called the crystallizer, in which sodium chloride crystals are recovered. Because of the influence of heavy rains and high humidity on the efficiency of such conventional solar processes, installations of seawater solar plants are usually restricted to such geographical regions which have low humidity and relatively low precipitation for at least a substantial portion of the year. Because of the reduced vapor pressure of salt brines, the presence of high humidity conditions severely restricts the ability to evaporate water to effect a concentration of such brines and the precipitation of salt therefrom. Similarly, in geographical regions which have heavy rains, dilution of the open ponds by such heavy rainfall drastically reduces the efficiency of salt production and may at times result in the complete loss of a salt crop from which the brine has been drained in preparation for harvest. For this reason, it is conventional practice in such seawater salt processes to maintain a relatively deep layer of brine over the salt bed to minimize dissolution of the salt crop as a result of heavy rainfalls.
The salt produced from seawater by solar evaporation is also characterized as containing substantial contaminating impurities including potassium chloride, calcium sulfate, magnesium chloride, magnesium sulfate the concentrations of which will vary somewhat depending on the geographical location. The presence of substantial amounts of such impurities may necessitate a purification of the harvested salt crop to increase its purity depending upon its intended end use.
The present invention overcomes the problems and disadvantages associated with prior art-type solar salt ponds and solar processes whereby the present invention produces a relatively high purity salt product, which is adaptable for operation in geographical areas in which the intensity and duration of sunshine, ambient temperatures, and precipitation are adverse to the production of solar salt, which can be geographically located at points remote from seawater supply, which generally requires less acreage, lower capital investment, and which is of simple and economical control and operation.